Immune-based therapy approaches that directly inhibit viral replication through activation of MHC-restricted mechanisms such as CD8+T cell effector function remain an area of active investigation. Here we propose to investigate a novel approach based on antiviral activity of a MHC non-restricted human cytotoxic T cell line, TALL-104 (CD3/TCR+ CD8+ CD56+ CD16-). TALL-104 cells are cytotoxic in vitro against a broad range of tumors across several species, without lysing cells from normal tissues. Importantly, TALL-104 cells have already been extensively characterized as an adoptive cell therapy in pre-clinical studies (over 10 years) including FDA approved phase I/II human clinical trials for the treatment of cancer patients. Our preliminary data in HIV-infected cultures show that TALL-104 cells can inhibit viral replication and kill HIV-infected cell in vitro. An increase in TALL-104 mediated killing of chronically infected lines ACH-1 and U1 was associated with HIV replication in these cells. Based on additional preliminary data documenting viral suppression of chronically infected T cells, we propose to test the hypothesis that TALL-104 cells can inhibit HIV-1 in primary lymphocytes and macrophages through activation of non-MCH-restricted mechanisms including direct cytotoxicity and secretion of antiviral soluble factors. In order to test our hypothesis, we will evaluate: 1. Analyze the antiviral activity of TALL-104 cells in primary cells, and more specifically: a) The activity of TALL-104 cells in decreasing viral replication in in vitro acutely infected X4 and R5 primary CD8-depleted T cells and monocyte-derived macrophages (MDM). b) The ability of TALL-104 cells to inhibit activation-induced viral replication in cells from HIV-1 infected patients. 2. Define the mechanisms involved in the anti-HIV activity by TALL-104 cells by: a) Analysis of the role of activating cytotoxic receptors (NCRs) NKp46 and NKG2D involved in triggering the killing HIV-infected. b) Analyzing the cytotoxic mechanisms responsible for killing HIV-infected cells: cytotoxic factors (granzymes and perforin) and cytotoxic mediators (Fas-L and tumor necrosis factor-related apoptosis-inducing ligand-TRAIL). c) Defining the role of potential soluble factors in the inhibition of viral replication (RANTES, MIP-1alpha, MIP-1beta and SDF-1). The work proposed represents a collaboration between The Wistar Institute, The University of Pennsylvania, Philadelphia FIGHT (Jonathan Lax Treatment Center).